Redirecting deflected boreholes



Jan. 16, 1951 R. K. WHITEHl-:AD ETAL REDIRECTING DEFLECTED BOREHOLES Filed Oct. 50, 1946 Patented Jan. 16, i951 UNITED STATES PATENT OFFICE I nannte-crine noaginotss y South Africa i Application october 30, 1946,. serial No. 706,686 In the Union of South Africa November' 2, 1945 1 claim. (ol. astanti This invention relates to the reedirection of boreholes with the object of 'guiding them nearer to the Vertical position. i

For this purpose it is lknown to provide 'a core drill with a pilot consisting Jof a rigid round rod extending ro'rn the mouth of the annular Icrown. Said pilot `is loosely supported vby the crown so tnat,'when allowed to hang freely 'from thellat= t'l-, it gravitationally assumes a position in which its length is more `vertical than the axfisof ythe crown, assuming the latter to be inclined. r'Ihe lower end of the pilot is adapted to be anchored to the bottom of -thebore hole. 1

In the process of rei-directing a bore hole by means of the pilot described, the drill -rods are held stationary 'near to the existing bottom of the bore hol-e but suiiiciently above said bottom as to enable the pilot to hang in a'position in which its lower end is eccentric to the axis of the hole and 'on the low side of thehole. `Said lower end of the pilot is thereupon anchored to the bot-- torn of the hole such eccentric position, by the means provided -for that purpose.l "Iheree upon the drill is rotated and red downwardly. With t's rlbwfi"enti tli'lllsl 'ecceh'trial-ly anchored and its upper en'd in the mouth `of the crown, the pilot constitutes a guide over which the drill travels 'and which coerces the drill first to ream out the wall of the hole on the low side of the latter and to rep-osition the drill with 'the axis off 'the crown positioned to intersect (or approximately intersect) 'the eccentric point at which the lower end of the pilot is anchored. During the lowering of the drill, the pilot relatively passes into the 'core barrel and remains therein at the top of any core that passes into said barirel.

It is an object of the present invention to provide a process and apparatus of this kind, in which the anchoring' of the lower end of the pilot rod is more positive land vreliable than heretofore. Another object is to enable the deviation to be made without substantial loss or core, and without the diminution of the core diameter which isunavoidable in other somewhat similar deviating methods.

According to this invention, a process of rediguiderod 'against the bottom'o'f the bore hole at a point eccentric-to the axis of the lowermost part 'oi the existing bore hole and on the low side vet' the hole, rotating the pilot drill while the drill rod 'line and the drill bit are held 'against rotation and simultaneously pressing the guide rod downwardly so that a pilot hole is drilled by the pilot drin; with the pilot drill anchored within the pilot hole and held against rotation, resuming Jdrilling with said drill bit along 'a new axis to wl'iich the drill bit is coerced by the guide rod, which axis is materially that of the anchored guide rod, Wh-ile theY vguide ro'd relatively 'enters the bore of the Idrill rods; and recovering the core ldrilled by the drill bit with the pilot drill embedded therein and 'the guide rod extending upwardly therefrom.

lis a feature of the 'invention that the rotary drill l'S dV'll by EtIlS f L 'WQ/13S? t'lb'l lated bya 4strearn oi water passed down the drill rod line, said turbine being mounted on said `pilot, the water vbeing exhausted from the turbine into the bore hole.

Apparatus according to the invention comprises a hollow guide rod adapted to be suspended from the lower lend o'f a hollow drill rod line and when "sfo sliependedl clzapa'blezofA limited swinging movement're'l'atively to the drill bit; a rotary ,pi'

lot drill axially mounted at that end of the guide rod which in use is lowermost., said pilot drill being considerably smaller in diameter than the bore hole; and means Ato rotate -said pilot drill independently off the drill bit.

An example of apparatus suitable to carry out the method of the invention is illustrated in the accompanying drawings, in which:

Flgurel is a partly sectioned elevation showing the pilot and the lower part of the -drill .rod line, the pilot being shown in the position at the bottom of the bore hole that it Voccupies after its lo\.er end has been anchored at the bottom of the hole.

Figure .Il is a similar view, showing the drill in its new alignment and roaming out the Aside of the bore hole; and Y Figure III-is a similar View at the stage at which the drill has been redirected and is in the process of drilling out a vfresh core.

In all the gures the lowermost part of the exis-ting bore hole is shown and is numbered 2. Such ljowermost part'of the bore hole is inclined to the'v-ertical, as is shown by the relationship of such part to the edges of the `drawing sheet.

The vcore barrel is numbered 3, and the drill bitor crown, whiclhfis numbered r4, is attached to thev lower end Vof it.

the said upper face B of the core lifter operate as Y elements of an universal joint between the crown 4 and the rod 6, and since the diameter of the pilot is materially less than that of the crown, permit the rod 6 limited swinging movement relatively to the crown.

The rod 6 is formed with a central bore 9 for passage of water from the core barrel 3 downwardly through the rod 6, and a rubber sleeve Eil is provided within the bore of the core barrel 3 and above the rod 6, to divertwater into the bore 9 of the rod 6 and to prevent substantial leakage between the head 'I of the rod 6 and the inne-l` wall of the crown 4. The lower face I i of the sleeve is formed complementarily to the shape of the upper surface of the head 1, and the passage I2 through the sleeve is substantially equal in diameter to the bore 9 of the rod 6.

In the lov/er end of the bore 9 of the pilot is accommodated the stator I3 of a water turbine I4, the rotor l5 of the turbine being fast with. a spindle i6 mounted in bearings I'I provided by the stator I3. The co-operating passages of the stator ISand the rotor I5 are respectively numbered i3d and' I5a.

Screwed axially into the rotor I5 is a rotary pilot drill I3, contructed to drill the kind of rock in which the bore hole for theV time being terminates. In the drawings, the body Vof the drill i8 is shown as set with diamonds I9.

In the use of the apparatus, the drill rod line is held-stationary near to the bottom of the 4 crown reams out the wall of the bore hole on the low side of the latter, as is shown in Figure II.

After the crown has reachedl the bottom 20 of the bore hole 2, continued drilling forms a new core at 24 (Figure III), the axis of which is coincident with the axis B-B. This core is recovered in the usual way, with the rod 6 attached to .the top of it. Y

The operation above described is repeated if and as often as may be necessary to bring the bore hole to the 'required degree of verticality, a convenient procedure being to drill some two and one half feet past thev anchored pilot drill I8 at each operation.

Re-direction of the crown 4 results in a shoulder or hump 25 being formed in the wall of the bore hole at about the point of re-direction. In order to eliminate this hump, the core barrel may, for afew feet above the crown, be set with cutting formations, for instance diamonds 26, to ream out the hump., The core barrel may be slightly reduced in diameter to make room for such cutting formations. Y

A particular feature of the operation of the invention is, as has been above stated', that there is no loss of core after` redirection of the bore hole. By this is meantthat the core 24V is of the usual core diameter. Obviously, duringthe inibore hole, but sufficiently above it to allow the Y rod 5 to hang from the crown ina position in which it is more vertical than the core barrel V3, with the pilot drill I8 eccentric to the axis of the hole and on its low side.

Full water is thereupon applied. Pressure on the upper surface 2l of the sleeve I0 forces the sleeve downwardly on to the head 1 of the rod 6, assists the mass of the pilot to hold the rod 6 against rotation, and tends to lock Vthe pilot inthe angular position it occupied relatively to the crown when water pressure was applied.

The water stream actuates the rotor I5 of the turbine Iii, and the rotor with the pilot drill I8, commences to rotate. Sediment, if present, is cleared away from the bottom 20 of the bore hole by the water evacuated from the turbine.

- The drill rod line is then lowered without rotation, whereupon the pilot drill I8 bores the pil-ot hole 22 in the bottom 20 of the bore hole.

' When the pilot drill has penetrated toits full depth, that is to say when the'lower face 23 of' the rotor is in Contact with the bottom 20 of the Y bore hole, the lower end of the rod 6 is firmly anchored in the pil-ot hole 2l and resumption of drilling causes the crown to be coerced by the anchored rod 6to follow the new axis B-B (Figure Il)V initiated by the pilotV drill I8, which axis is'nearer lto verticality than is the axis A-A (Figure II) of the bore hole 2 by an angular extent which is indicated by a, while the rod 6 relatively' enters the core barrel 3.

While following such new axis B-B, the

tial process of re-direction, that is to say when the crown is reaming out theV wall of the bore hole, the material reamed out is not recovered.

We claim: K Y The process of re-directing an inclined bore hole nearer to verticality, which comprises the steps of suspending a straight guide rod from the lower end of a hollow drill rod line to hang gravitationally more nearly vertical than is said lower end, lowering the drill rod line to bring a rotary pilot drill at the lower end of the guide rod against the bottom of the'bore hole at a point eccentric to the axis of the lowermost part of the existing bore hole and, on the low side of the hole, rotating the pilot drill while the drill rod line and the drill bit are held against rotation and simultaneously pressing theY guide rod downwardlyV so that a pilot hole is drilled by the pilot drill; withthe pilot drill anchored ywithin the pilot hole and held against rotation, resuming drilling with said drill bit along a new axis to whichY the drill bit is coerced by the guide rod, which vaxis is materially that of the anchored guide rod, while Vthe guide rod relatively enters the bore of the drill rods; and recovering the core drilled by the drill bit, with the pilot drill embedded therein and the guide rod extending upwardly therefrom.

RANDOLPH KNOX WHITE-HEAD. GEORGE BERNARD WELDON.

REFERENCES crrnn The following references are of recordin the fileof thisrpatent: Y

UNITED STATES PATENTS Quintrell Dec, 16, 

